Constant-speed drive device



April 17, 1934. g, PACKER 1,955,309

CONSTANT SPEED DRIVE DEVICE Filed Feb. 7, 1931 2 Sheets-Sheet 1 Fig.1

INVENTOR Lewis G Packer.

/ ATTORNEY April 17, 1934. 1.. c. PACKER 1,955,309

CONSTANT SPEED DRIVE DEVICE Filed Feb. 7, 1931 2 Sheets-Sheet 2 Fig.3.

INVENTOR 40 Lew 2's 6. Packer.

ATTORNEY WITNESSES:

Patented Apr. 17, 1934 UNITED STATES ATENT FFECE CONSTANT-SPEED DRIVE DEVICE Application February 7, 1931, Serial No. 514,190

11 Claims.

My invention relates to constant-speed driving devices, and it has particular relation to such devices utilizing a variable-speed electric motor, and particularly a universal motor, in combination with a centrifugal clutch, all mounted together as a single unit in a common frame.

A more particular object of my invention is to provide a driving means of the aforesaid character, suitable for application to adding or calculating machines, as set forth more in detail in the joint application of R. Ehrenfeld and myself, Serial No. 514,185, filed February 7, 1931.

One object of my invention is to provide a compact unit consisting of an electric motor and a centrifugal clutch, having but a single shaft, or shaft-receiving hub, projecting therefrom, and running at a constant speed, notwithstanding the fact that the motor operates at a very variable speed.

A further object of my invention is to provide a motor-unit having an integral cylindrical housing for a centrifugal clutch.

With the foregoing and other objects in view, my invention consists in the details and combinations thereinafter described and claimed, and illustrated in the accompanying drawings, wherein Figure 1 is a longitudinal, cross-sectional view through the motor-clutch unit of my invention, in a preferred form of embodiment,

Fig. 2 is a transverse sectional view through the clutch, on the section plane indicated by the line IIII in Fig. 1,

Fig. 3 is a transverse sectional view through one of the bearings, the section plane being indicated by the line IIIIII on Fig. 1, and

Fig. 4 is a diagrammatic view indicating the electric wiring connections to my motor.

As set forth more in detail in the above-named joint application on the calculating machine, the achievement of a satisfactory constant-speed, and small-power, drive for such devices as calculating machines, has never heretofore been consummated. Such apparatus, requiring smallpower electric driving means, is sold, not only in the-United States, but a. very considerable portion of the total sales is for foreign use, and means must be provided whereby the machine may operate on direct-current of many voltages, on alternating-current of many voltages and frquencles and of ttimes on supply-means on which the voltage or the frequency is very far from constant, and all this must be accomplished on a device in which the loadis very variable. Preferably, also,

my constant-speed drive is applied to a machine, such as an adding machine, in which the motor is not left running idle between strokes, but the motor is deenergized at the completion of each key operation, so that a motor having an ex tremely high rate of acceleration is required.

Previous attempts on the solution of the foregoing problems have involved the use of centrifugal make-and-brake devices for holding the motor-speed constant, which have not altogether succeeded in holding the speed constant and have proved to be troublesome, besides requiring several different sizes and windings of motors to take care of the complete range of requirements as to voltage and frequency. Another attempted solution of the problem has involved the use of a variablespeed motor in conjunction with a centrifugally controlled braking means for always imposing sufiicient load on the motor to hold its speed down to a predetermined value; but this has involved a cumbersome design to provide sufficient heat-capacity in the brake, it has involved the use of a larger electric motor than would otherwise be required, because of the fact that at least half of its energy is absorbed in the brake, the brake has developed defects resulting in pumping" of the speed and any defect such as an oily drum or worn-out lining, has resulted in an over-speed of the driven device, with its attendant dangers.

According to my invention, as shown in the accompanying drawings, I provide a variablespeed, universal, (alternating or direct current) series commutator motor 5 having a commutatortype armature 6 provided with a commutator cylinder 7, brushes 8 bearing on said commutator cylinder, a motor shaft 9, and two journal bearings l0 therefor. The stator member of the motor, besides carrying the brushes and bearing housings, is provided with a magnetic field structure having an exciting field winding 12 and preferably, also, a. distributed compensating winding 13, particularly in the larger sizes of the motor.

Since the motor is applied to devices having frequently long intervals of inattention as to oiling, and as the primary object of my invention is to provide a constant-speed drive which is as fool-proof as possible, I prefer to lubricate each of the journal bearings by a side-wick oiler 15 comprising a length of thick wool yarn 16 bearing against the under surface of the motor shaft 9 and substantially filling an oil reservoir in the shape of a horizontal hole 18 drilled through a solid portion of the bearing housing. The wool yarn 16, comprising the wick, is saturated with oil, and as it substantially fills the oil reservoir, it prevents leakage of oil and will retain its lubricating properties for long periods of time.

At the rear end of the motor (opposite the commutator), the motor shaft 9 is slightly extended and terminates in a drum 20, constituting the driving member of my centrifugal clutch 21. The drum is surrounded by a plurality of friction and weight members 22 which are guided between a plurality of spaced arms 23 of a driven cage member 24, having, in addition to said arms, a radial disk portion 25 and an outwardly extending hub 26 having a set screw 27, or other means accessible from the outside of the cage member, for driving engagement with a driven shaft 28 which is shown in Fig. 4. The weight members 22 are pressed against the drum by one or more of garter springs 29, so that the weights begin to fly off from the shaft at a critical speed, at which the centrifugal force just overcomes the tension of the springs, so that the driven cage member 24 is driven at this constant critical speed while the driving shaft operates at much higher speeds. The details of the clutch not herein claimed are described and claimed more particularly in the application of C. R. Libby, Serial No. 501,014, filed December 9, 1930.

Preferably, the cage member 24 is provided with a cylindrical guard member 31 which is secured thereto and rotates therewith, the same being spaced only a very short distance from the springs 29, so as to prevent one or both of the springs from flying out unequal at one point of the circumference. The cylindrical rotating guard member 31 is preferably provided with an end flange 32 which projects inwardly so as to enclose the springs 29 and weight members 22, so that the cage member is retained against accidental, longitudinal displacement, by means of the weights 22 which are normally held friction-tight against the drum 20 when the motor is at rest. This enables the motor-unit to be handled freely.

According to my invention, the motor 5 is provided with a housing 34 which has an integral cylindrical extension 35 over the clutch member 21, thus preventing any possibility of danger from contact with the rotating cage member or rotating cylindrical guard 31. The cylindrical housing extension 35 may be provided with one or more holes 36 for ventilating the clutch-member 21 and for providing access to a set screw 37 which secures the drum 20 to the motor-shaft 9.

The leads for the motor preferably enter the motor housing 34 at the front or commutator end, as indicated at 38. The motor circuit is interrupted, however, and extended out to a detachable plug 39 underneath the cylindrical extension 35 at the rear end, whereby the motor may also be controlled by means of a switch 40 (Fig. 4) located in or on the machine which is driven by the motor-unit. This disposition of the leads and connections makes a most convenient arrangement, particularly when the motor is mounted on the frame of the machine which it drives, by the same screws 41 as are utilized for holding the detachable plug 39 in place.

I claim as my invention:

1. An electric motor-unit comprising; a motorframe having a tubular cylindrical extension at the rear end and an intermediate field member; a motor-rotor member comprising a shaft, bearings at each end, an armature member, the shaft extending slightly beyond the bearing at the rear end, and a cylindrical drum mounted on said shaft-extension within said tubular cylindrical extension; and a centrifugal clutch mechanism cooperating with said drum and held in frictional engagement therewith when the motor is not in use, the same comprising a driven member having a radial portion and a plurality of frictional weight members carried thereby and disposed concentrically around said drum, spring means associated with said frictional weight members and pressing the same against the drum at all speeds below a critical operating speed of the centrifugal clutch, and means for preventing axial separation of said driven member and said frictional weight members, whereby the frictional engagement of said frictional weight members on the drum holds the driven member against displacement out from under said cylindrical frame-extension when the motor is not in use, said radial driven-member portion being provided with a central hub having means accessible outside of said clutch mechanism for operatively engaging a disconnectible driven shaft substantially coaxial with the motor shaft.

2. An electric motor-unit comprising, a motorframe having a tubular cylindrical extension at the rear end, a motor-rotor member comprising a shaft, bearings at each end, and an armature member, the shaft extending slightly beyond the bearing at the rear end, and a cylindrical drum mounted on said shaft-extension within the tubular cylindrical extension; and a centrifugal clutch mechanism co-operating with said drum and held in frictional engagement therewith when the motor is not in use.

3. A constant-speed driving-unit comprising a relatively high-speed, variable-speed rotatable driving member having an extending shaft terminating in a drum; and a centrifugal clutch mechanism co-operating with said drum and held in frictional engagement therewith when the driving-unit is not in use, the same comprising a radial driven member having spring-restrained centrifugal friction means bearing on said drum for driving the same, and having a central hub substantially co-axial with the driving-shaft, said hub having means accessible outside of said clutch mechanism for operatively engaging a disconnectible driven shaft substantially coaxial with the driving shaft.

4. A constant-speed driving-unit comprising a relatively high-speed, Variable-speed universal electric motor having an extending shaft terminating in a drum; and a centrifugal clutch mechanism co-operating with said drum and held in frictional engagement therewith when the motor is not in use, the same comprising a radial driven member having spring-restrained centrifugal friction means bearing on said drum for driving the same, and having a central hub, substantially co-axial with the driving-shaft, having means accessible outside of said clutch mechanism for operatively engaging a disconnectible driven shaft;

said motor being further characterized by a stator 1 driven member having spring-restrained centrifugal friction means bearing on said drum for driving the same, and having a central hub, substantially co-axial with the driving-shaft, having means accessible outside of said clutch mechanism for operatively engaging a disconnectible driven shaft; said motor being further characterized by a stator frame having a tubular extension over said clutch mechanism, said extension having a hole for providing access to the setscrew for said drum.

6. A constant-speed motor-unit comprising a variable-speed motor and a constant-speed centrifugally responsive friction-clutch, and a common housing for said motor and clutch, characterized by the fact that the common housing has a portion overhanging said clutch and provided with an opening for providing access to the inner end of the clutch.

'7. A constant-speed driving-unit comprising a variable-speed source of motive power and a constant-speed centrifugally responsive frictionclutch, and a common housing for said source of motive power and said clutch, characterized by 1 the fact that the common housing has a portion overhanging said clutch and provided with an opening for providing access to the inner end of the clutch.

8. A constant-speed driving-unit comprising a variable-speed source of motive power having a shaft, bearings for said shaft at each end of said source of motive power, a frame for said source of motive power, said frame constituting a means for holding said bearings, said frame having a tubular cylindrical extension beyond one of said bearings at one end, said shaft extending slightly beyond said bearing at said end and a cylindrical drum mounted on said shaft-extension within the tubular cylindrical extension; and a centrifugal clutch mechanism co-operating with said drum and held in frictional engagement therewith when the driving-unit is not in use.

9. An electric motor-unit comprising, a motorframe having a tubular cylindrical extension at the rear end, a motor-rotor member comprising a shaft, bearings at each end, and an armature member, the shaft extending slightly beyond the bearing at the rear end, and a cylindrical drum mounted on said shaft-extension within the tubu- 1; lar cylindrical extension; and a centrifugal clutch frame is provided with an opening for providing access to the inner end of said drum.

10. A constant-speed driving-unit comprising a variable-speed source of motive power having a shaft, bearings for said shaft at each end of said source of motive power, a frame for said source of motive power, said frame constituting a means for holding said bearings, said frame having a tubular cylindrical extension beyond one of said bearings at one end, said shaft extending slightly beyond said bearing at said end and a cylindrical drum mounted on said shaft-extension within the tubular cylindrical extension; and a centrifugal clutch mechanism co-operating with said drum and held in frictional engagement therewith when the driving-unit is not in use, characterized by the fact that the tubular cylindrical extension of the frame is provided with an opening for providing access to the inner end of said drum.

11. A constant-speed driving-unit comprising a variable-speed source of motive power having a shaft, bearings for said shaft at each end of said source of motive power, a frame for said source of motive power, said frame constituting a means for holding said bearings, said frame having a tubular cylindrical extension beyond one of said bearings at one end, said shaft extending slightly beyond said bearing at said end, and a cylindrical drum mounted on said shaft-extension within said tubular cylindrical extension; and a centrifugal clutch mechanism cooperating with said drum and held in frictional engagement therewith when the driving unit is not in use, the same comprising a driven-member having a radial portion and a plurality of frictional weight members carried thereby and disposed concentrically around said drum, spring means associated with said frictional weight members and pressing the same against the drum at all speeds below a critical operating speed of the centrifugal clutch, and means for preventing axial separation of said driven member and said frictional weight members, whereby the frictional engagement of said frictional weight members on the drum holds the driven member against displacement out from under said cylindrical frameextension when the motor is not in use, said radial driven-member portion being provided with a central hub having means accessible outside of said clutch mechanism for operatively engaging a disconnectible driven shaft substantially coaxial with the driving shaft.

LEWIS C. PACKER. 

